1. Field of the Invention
This invention relates to a control process for the driving of a fuel pump of an internal combustion engine that is installed, in particular, in a motor vehicle. This invention relates more particularly to a control process intended to facilitate the pressurization of the fuel circuit of the engine before starting the latter.
2. Discussion of the Background
The supply circuit of an internal combustion engine traditionally includes a circuit for supplying the fuel under pressure from a storage tank to the electronic injectors controlled by an electronic engine control which determines the amount of fuel to be injected depending on the operating conditions of engine. Traditionally, the injectors are supplied with fuel under a constant pressure, the amount of injected fuel being determined by the duration of the opening of the injectors or injection time.
The fuel circuit is equipped with an electric pump which delivers the fuel at a given pressure regardless of the operating speed of the engine. The use of this pump is directly controlled by the electronic engine control system which determines the operating range of the pump so as to prevent any danger of accidental leakage of the fuel. Thus the pump is actuated only after the cranking of the starter and it is stopped immediately after engines is stopped.
To facilitate the starting of the engine, however, the prestarting of the fuel pump is allowed for a predetermined duration, also called delay time, as soon as contact has been made, i.e., as soon as the engine control system is switched on. Thus, the fuel circuit is already under pressure when the starter is actuated, which makes it possible to inject immediately the desired amounts of fuel. The delay time 10 traditionally is constant for a given engine and is relatively short, on the order of a few seconds, for reasons of safety. It has been determined that such a delay time is insufficient to assure the pressurizing of the fuel circuit under certain circumstances and particularly when the fuel circuit is empty, which is the case when a motor vehicle comes off the production line.
Therefore, under these particular circumstances, a relatively long actuation of the starter results in a long operation of the fuel pump which is necessary for the fuel pressure to rise and thus make it possible to inject sufficient amounts of fuel. This relatively prolonged actuation of the starter can prove damaging to the service life of the electric battery and of the starter of the vehicle which are very heavily acted on.